The present invention relates to a plowing depth detecting system for detecting an actual plowing depth of a rotary plow with respect to the ground plowed by the rotary plow, the system being operable based on distance data relative to the ground measured by sensor means attached to the rotary plow.
A known plowing depth detecting system of the above-described type includes sensor means forwardly or rearwardly of the rotary plow and detects the actual plowing depth based on variations of distance between the sensor means and ground surface. Where the sensor means is mounted forwardly of the rotary plow, the actual plowing depth is detected by measuring a difference between distances to the ground before and after the rotary plow is lowered (that is, by measuring a distance by which the rotary plow is lowered from the ground surface). However, this construction has difficulties in constantly detecting a precise actual plowing depth owing to undulations of the ground, weeds and the like. On the other hand, where the sensor means is mounted rearwardly of the rotary plow, errors in detecting the actual plowing depth occur with rises of the ground surface after plowing and with changes in posture of the sensor means.